Heterostructures that are assembled by interfacing two-dimensional (2D)
materials offer a unique platform for the emerging devices with
unprecedented functions. The attractive functions in heterostructures
that are usually absent and beyond the single layer 2D materials are
largely affected by the inherent lattice mismatch between layers. Using
nonequilibrium molecular dynamics simulations, we show that the phonon
thermal transport in the graphene MoS2 bilayer heterostructure is
reduced by the lattice mismatch, and the reduction can be mitigated well
by an external tension, weakening the effect of inherent mismatch-
induced strain on thermal conductivity. Mechanical analysis in each
layered component indicates that the external tension will alleviate the
lattice mismatch-induced deformation. The phonon spectra are also
softened by the applied tension with a significant shift of frequency
from high to low modes. A universal theory is proposed to quantitatively
predict the role of the lattice mismatch in thermal conductivity of
various bilayer heterostructures and shows good agreement with
simulations.